Fuel systems for driving machinery or engines include various components such as a fuel tank, fuel lines for delivering the fuel to the engine, fuel pumps for pumping the fuel from the tank through the fuel lines to the engine, and fuel injectors for injecting fuel into a respective cylinder, for example. Fuel leaks (both liquid and vapor) may occur in any part of the fuel system and it is desirable to be alerted to such leaks at the earliest possible moment. Furthermore, due to environmental concerns and engine operating efficiency, it is desirable to prevent passage of leaked fuel into the atmosphere or into or onto surrounding components.
For example, one potential source of a fuel leak is at the mechanical rotary or reciprocating pump seal of a high pressure fuel pump in a vehicle fuel system. Direct injected gasoline engines require fuel pressures as high as 20 MPa to operate. The fuel pressure is normally generated by a mechanical engine-driven fuel pump. This high pressure fuel pump can be either directly mounted to the engine and driven from a dedicated cam lobe on the camshaft or a coupling driven from the end of the crankshaft, or remotely mounted and driven by the engine serpentine or a dedicated belt coming off the engine.